Nitrogen (N) inputs and outputs were measured over 3 years in a trial with four farmlets teach with 16 randomly-allocated 0 4 ha paddocks) on permanent white clover/ryegrass pastures which were grazed throughout the year by dairy cows near Hamilton, New Zealand. Three farmlets were stocked at 3.3 cows/ha and received nominal rates of N fertilizer (urea in 8-10 split applications) of 0, 200 or 400 kg N/ha per year. A fourth farmlet with 4.4 cows/ha received 400 kg N/ha per year and was supplemented with maize grain during the first two years. Nitrogen balances were calculated, with Sigma N inputs approximate to Sigma N outputs. Annual inputs from N-2 fixation were 99-231 kg N/ha in the 0 N farmlet, but declined to 15-44 kg N/ha in the 400 N farmlets. The main N outputs tin kg N/ha per year) were in milk (72-126), nitrate leaching (20-204), and transfer of N via cow excreta from pastures to lanes and milking shed (54-92). Gaseous losses by denitrification (3-34) and volatilization (15-78) were smaller than the other N outputs but increased significantly with N fertilizer application. In the maize-supplemented farmlet, N outputs in milk were 31% higher than in the corresponding non-supplemented 400 N farmlet, whereas leaching losses averaged 17% lower during the 2 years of supplementation. In the N-fertilized farmlets, estimated N balances were influenced by inclusion of the transitional N processes of immobilization of fertilizer N into the soil organic N pool (estimated using N-15 at 42-94 kg N/ha per year) and the contribution from mineralization of residual clover-fixed N in soil not accounted for in the current estimates of N-2 fixation (estimated at up to 70 % of measured N-2 fixation or 46 kg N/ha per year). However, these processes were counteracting and together were calculated to have only a small net effect on total N balances. The output of N in products (milk, meat and feed) relative to the total N input averaged 26 % in the 400 N farmlets, and is compared to that measured for commercial intensively-managed dairy farms in England and the Netherlands (14-20 %). The 0 N farmlet, which was reliant on N-2 fixation as the sole N input, was relatively very N-efficient with the milk production being 83 % of that in the 400 N farmlet (at 3.3 cows/ha) and the N output in products relative to total N input averaging 52%.
Potted 1.5-year-old apricot plants (Prunus armeniaca L.), growing under polycarbonate glasshouse conditions with a cooling system, were subjected to two successive water stress/recovery periods until pre-dawn leaf water potential (Psi(pd)) reached values between -2.0 and -2.5 MPa, during summer 1996. Control plants were irrigated daily to maintain the: soil matric potential at c. -20 kPa. Water stress limited plant growth and induced a significant reduction in leaf area, caused by mature leaf abscission. The parallel behaviour of leaf turgor potential and epinasty in stressed plants indicated that these movements are turgor-dependent. Osmotic adjustments of 0.27 and 0.60 MPa were observed at the end of the first and second stress period, respectively. Relative apoplastic water content (RWCa) values were high, ranging from 27 to 42 %, and were not affected by water stress. The rapid decrease in leaf conductance (g(1)) from the beginning of the stress periods, together with the delay in stomatal reopening after rewatering the plants, indicated that stomatal behaviour was not a simple passive response to water deficits. Net photosynthesis decreased only at the end of both stress periods and recovered quickly. These observations indicate that leaf productivity may be affected only slightly by short-term water stress. The results indicate that drought resistance in apricot is based mainly on avoidance mechanisms, such as stomatal control, epinasty and limitation of transpiration by reducing leaf area. However, some tolerance characteristics, including osmotic adjustment, high RWCa and low leaf osmotic potential at turgor loss point (Psi(tlp)) values were observed.
The effect of environmental conditions immediately before anthesis on potential grain weight was investigated in wheat at the experimental held of the Faculty of Agronomy (University of Buenos Aires, Argentina) during 1995 and 1996. Plants of two cultivars of wheat were grown in two environments (two contrasting sowing dates) to provide different background temperature conditions. In these environments, transparent boxes were installed covering the spikes in order to increase spike temperature for a short period (c. 6 days) immediately before anthesis, i.e. between ear emergence and anthesis. In both environments, transparent boxes increased mean temperatures by at least 3.8 degrees C. These increases were almost entirely due to the changes in maximum temperatures because minimum temperatures were little affected. Final grain weight was significantly reduced by higher temperature during the ear emergence-anthesis period. It is possible that this reduction could be mediated by the effect of the heat treatment on carpel weight at anthesis because a curvilinear association between final grain weight and carpel weight at anthesis was found. This curvilinear association may also indicate a threshold carpel weight for maximizing grain weight.
The effects of plant density on the growth and yield of winter oilseed rape (Brassica napus) were examined in a series of five multifactorial experiments at Rothamsted Experimental Station between 1984 and 1989. Plant densities, manipulated by changing the seed rate and row spacing, or because of overwinter losses, ranged from 13.5 to 372 plants/m(2). Normalized yields for the multifactorial plots increased with densities up to 50-60 plants/m(2). In very high density plots in 1987/88, yield decreased as density increased > 150 plants/m(2). Plants grown at high density had fewer pod-bearing branches per plant but produced more branches/m(2). Branch dry matter (DM) per plant was decreased by 42 %, the number of fertile pods per plant and pod DM/plant by 37 %. There was no effect of density on the number or DM of pods/m(2). Over 74 % of the fertile pods were carried on the terminal and uppermost branches of plants grown at high density in 1987/88 compared with only 34% in plants grown at low density in 1988/89. Seed DM/plant decreased with increase in density but seed size (1000-seed weight) increased. There was no effect of density on seed glucosinolate or oil contents.
The solvent extraction of alkanes from faeces and herbage samples at two different temperatures (cold: 15-25 degrees C and hot: 65 degrees C) was studied in four samples of different matrix types (cattle faeces, sheep faeces, hill grass and heather), in two experiments performed at Villaviciosa, Asturias, Spain in 1994. Two internal standards (IS) of different chain length (C-22 and C-34) were used to estimate alkane concentrations. Significant differences were detected in alkane extraction derived from temperature of extraction, IS and sample matrix. At the cold temperature, long-chain alkane extraction was not complete, resulting in errors in the estimation of alkane concentration when a long-chain alkane (C-34) was used as the only internal standard. However, under hot extraction, long-chain alkanes were completely extracted by the heptane, although estimates made with C-22 or C-34 as IS were not identical. These results suggest that it would be appropriate to use two internal standards with short and long carbon chain, such as C-22 and C-34, in routine analyses to establish the completeness of alkane extraction, even under hot conditions, by calculating the relative ratio of both IS in extracts compared to the original C-22:C-34 ratio added to the samples. Any increase or decrease in expected peak areas could be adjusted for all the alkanes in the extracts, and the accuracy of alkane concentration measurements (and therefore the reliability of estimates of intake and especially of diet selection) would be improved.
A grazing experiment, conducted for 55 days (from 4 March to 29 April) in the late summer/autumn of 1997, at Massey University, Palmerston North, New Zealand, compared the reproductive efficiency and wool growth of ewes grazing Lotus corniculatus (birdsfoot trefoil) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) dominant pasture (pasture). Half the ewes grazing each forage were given daily oral polyethylene glycol (PEG:molecular weight 3500) supplementation to inactivate the condensed tannins (CT) in lotus. A rotational grazing system with 200 mixed age ewes (54.2 +/- 0.88 kg/ewe; 50 ewes/treatment) was used. The effect of forage species and PEG supplementation upon voluntary feed intake (VFI), concentration of plasma metabolites, reproductive efficiency, wool production and wool characteristics was measured during two synchronized oestrous cycles. The ewes were restricted to maintenance feeding for the first 12 days of each oestrous cycle and then increased to ad libitum for the 6 days prior to and including ovulation. Lotus contained 17 g total CT/kg dry matter (DM) in the diet selected. There were only trace amounts of total CT in pasture. In vitro organic matter digestibility (OMD) was higher for lotus (0.82 v. 0.74) than for pasture, whilst lotus contained less nitrogen (N; 37.8 v. 44.5 g/kg OM). Mean ovulation rates (OR) for CT-acting and PEG sheep grazing pasture and lotus were respectively 1.33 v. 1.35 and 1.78 v. 1.56, with corresponding lambing percentages being 1.36 v. 1.36 and 1.70 v. 1.42. Fecundity (number of corpora lutea/ewe ovulating) was greater for ewes grazing lotus than pasture (P < 0.01), and tended to be greater for CT-acting than for PEG sheep grazing lotus(P = 0.06). In unsupplemented sheep, ewes grazing lotus had increased plasma concentrations of branched chain amino acids (BCAA; 57%) and essential amino acids (EAA; 52%) compared to ewes grazing pasture. In ewes grazing pasture, PEG administration had no effect on plasma concentrations of urea and free amino acids, VFI, reproductive efficiency and wool production. However, in sheep grazing lotus, plasma concentrations of urea were significantly lower and concentrations of most amino acids were significantly higher for CT-acting than for PEG supplemented ewes (CT not acting); there was no difference in VFI between these two groups. Compared to ewes grazing pasture, ewes grazing lotus had similar VFI but produced more wool with longer staples and thicker fibre diameter, with there being no effect of PEG supplementation. It was concluded that feeding lotus increased the efficiency of both reproduction and wool production without an increase in VFI, and that a possible cause was the action of CT in increasing plasma EAA and especially BCAA concentration.
In a preliminary experiment, 74 faba bean genotypes including winter genotypes (autumn-sown) and spring genotypes (spring-sown) and isogenic population pairs (tannin-containing v. tannin-free and vicine/convicine-high v. vicine/convicine-low), were analysed for the chemical composition of their seeds. A large variability was found for the main constituents (starch, protein and fibre). Autumn-sown genotypes contained 2.3 % less proteins but 2.5 % more starch in the seed dry matter (DM) than spring-sown genotypes. The ve gene, which lowers the vicine and convicine contents, did not significantly modify the main seed components in the isogenic comparisons. The ttl and zt2 genes, which eliminate condensed tannins in the seed coats, lowered by 2.1 % the proportion of the seed coat in the DM. In the isogenic comparisons, the zt2 gene had a stronger effect than ttl in reducing the total seed fibre and increasing the protein content. In a second experiment, from the original 74 genotypes, 12 contrasted genotypes were selected and multiplied for animal nutrition trials. Their chemical analysis confirmed the variability between the faba bean categories observed in Expt 1, but detailed chemical analyses illustrated the variability in amino acid, fatty acid, amylose and oligosaccharide composition, trypsin inhibitory activity, condensed tannins, lectins and phytic phosphorus contents.
Sixty Holstein/Friesian dairy cows, 28 of high genetic merit and 32 of medium genetic merit, were used in a continuous design, 2 (cow genotypes) X 4 (concentrate proportion in diet) factorial experiment. High and medium merit animals had Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year (PTA(95) fat plus protein), of 43.3 kg and 1.0 kg respectively. Concentrate proportions in the diet were 0.37, 0.48, 0.59 and 0.70 of total dry matter (DM), with the remainder of the diet being grass silage. During this milk production trial, 24 of these animals, 12 from each genetic merit, representing three animals from each concentrate treatment, were subject to ration digestibility, and nitrogen and energy utilization studies. In addition, the efficiency of energy utilization during the milk production trial was calculated. There were no genotype x concentrate level interactions for ally of the variables measured (P > 0.05). Neither genetic merit nor concentrate proportion in the diet influenced the digestibility of either the DM or energy components of the ration (P > 0.05). When expressed as a proportion of nitrogen intake, medium merit cows exhibited a higher urinary nitrogen output and a lower milk nitrogen output than the high merit cows. Methane energy output, when expressed as a proportion of gross energy intake, was higher for the medium than high merit cows (P 0.05). However when k(1) was calculated using the production data from the milk production trial the high merit cows were found to have significantly higher k(1) values than the medium merit cows (0.64 v. 0.59, P < 0.05) while k(1) tended to fall with increasing proportion of concentrate in the ration (P < 0.05). However in view of the many assumptions which were used in these latter calculations, a cautious interpretation is required.
The air quality in 82 German livestock buildings was investigated, using ammonia as a gaseous indicator. The ammonia concentrations were measured hourly and a 24 h mean was calculated. In cattle houses the mean ammonia measurement ranged between 37 ppm in calf houses (n = 16), 4.7 ppm in beef units (n = 10) and 6.4 ppm in dairy cattle houses (n = 8). In pig buildings the highest mean concentrations of 15.9 ppm were found in fattening pig livestocks (n = 8). In sow (n = 16) and weaner livestock buildings (n = 8) the averaged ammonia concentration varied between 13.4 ppm and 9.1 ppm, respectively. Within poultry houses, broiler flocks (n = 8) were associated with ammonia concentrations of 21.2 ppm. On the other hand, livestock buildings containing laying hens (n = 8) showed the lowest ammonia concentrations of all, namely 2.7 ppm. A significant positive correlation between temperature, relative humidity and ammonia concentrations could be found in poultry houses. Assuming an ammonia threshold limit value of 15 ppm, although no cattle house in this study exceeded this recommended limit, 31% of all the pig and poultry units investigated did, indicating a need for improved housing conditions in the future.
Twenty-eight high genetic merit and 32 medium genetic merit Holstein/Friesian dairy cows with Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year (PTA(95) fat plus protein) of 43.3 and 1.0 kg respectively, were used in a continuous design, 2 (cow genotypes) x 4 (concentrate proportion in diet) factorial experiment consisting of eight treatments. Concentrate proportions in the diet were 0.37, 0.48, 0.59 and 0.70 of total dry matter (DM), while the forage component of the diet was grass silage. Diets were offered ad libitum in the form of a complete diet. Animals remained on these concentrate regimes for a mean of 84.7 days before completing a standard 98-day grazing period. At pasture, cows received either 5.0 or 6.0 kg concentrate daily according to turnout date. There were no significant genotype x nutrition interactions for any of the variables examined during either the indoor feeding or post-turnout grazing periods (P 0.05), while high merit cows continued to have higher outputs of milk and milk constituents (P < 0.001). Body tissue reserves of both genotypes changed little during the grazing period. It is likely that the higher milk yields of the high merit cows can be attributed both to their higher DM intakes and their ability to partition a greater proportion of the nutrients consumed into milk rather than body tissue reserves. Although statistically both high and medium merit cows responded in a similar manner to an increasing proportion of concentrate in the diet, high merit cows did exhibit a 49% greater fat plus protein yield response during the indoor period, compared to animals of medium genetic merit, perhaps hinting at the existence of a genotype x nutrition interaction.
The effect of late season insect infestation on seed yield, yield components, oil content and oil quality of two canola species (Brassica napus L. and B. rapa L.) and two mustard species (B. juncea L. and Sinapis alba L.) was examined over 2 years. In each year, ten genotypes from each species were evaluated with late season insects controlled with either methyl parathion or endosulfan insecticides, and without insecticides. Major late season insect damage in 1992 was caused by cabbage seedpod weevil (Ceutorhynchus assimilis Paykull), while diamondback moth (Plutella xylostella L.) and aphids (primarily cabbage aphids, Brevicoryne brassicae L.) were major insect pests in 1993. Insecticide application was very effective in controlling diamondback moth larvae and adult cabbage seedpod weevils, but only partially effective in controlling aphids. Higher numbers of diamondback moth larvae were observed on mustard species compared to canola species. S. alba was completely resistant to cabbage seedpod weevil and there was no damage due to this pest observed. Aphid colonization was observed on plants from all species, but infestation on S. alba and B. rapa occurred too late to have a major effect on seed yield. Seed oil content of canola species was significantly reduced by insect damage although oil quality (indicated by fatty acid profile) was not affected by insect attack. Uncontrolled insect infestation reduced seed yield of canola species by 37 and 32% in B. napus and B. rapa, respectively. Least yield reduction occurred in S. alba, where average yield reduction from plants in untreated control plots was < 10% of insecticide treated plants. S. alba, therefore, has good potential as an alternative crop suitable for northern Idaho because it can be grown with reduced late season insecticide application.
In four field experiments, the effects of single nitrogen (N) applications at planting on yield and nitrogen uptake of potato (Solanum tuberosum L.) was compared with two or three split applications. The total amount of N applied was an experimental factor in three of the experiments. In two experiments, sequential observations were made during the growing season. Generally, splitting applications (up to 58 days after emergence) did not affect dry matter (DM) yield at maturity and tended to result in slightly lower DM concentration of tubers, whereas it slightly improved the utilization of nitrogen. Maximum haulm dry weight and N content were lower when less nitrogen was applied during the first 50 days after emergence (DAE). The crops absorbed little extra nitrogen after 60 DAE (except when three applications were given). Soil mineral N (0-60 cm) during the first month reflected the pattern of N application with values up to 27 g/m(2) N. After 60 DAE, soil mineral N was always around 2-5 g/m(2). The efficiency of N utilization, i.e. the ratio of the N content of the crop to total N available (initial soil mineral N + deposition + net mineralization) was 0.45 for unfertilized controls. The utilization of fertilizer N (i.e. the apparent N recovery) was generally somewhat improved by split applications, but declined with the total amount of N applied (range 0.48-0.72). N utilization and its complement, possible N loss, were similar for both experiments with sequential observations. Separate analysis of the movement of Br- indicated that some nitrate can be washed below 60 cm soil depth due to dispersion during rainfall. The current study showed that the time when N application can be adjusted to meet estimated requirements extends to (at least) 60 days after emergence. That period of time can be exploited to match the N application to the actual crop requirement as it changes during that period.
The effect of drought stress in isolation, or in combination with beet yellows virus infection, on sugar beet growth was studied in the field and glasshouse. Drought reduced total plant weight by 26%, due to 20 and 29% reductions in foliage and storage root yields respectively. Sugar extraction efficiency was depressed by an increase in amino-nitrogen impurities. Drought did not limit water extraction depth, despite decreasing lateral root growth in proportion to total weight. During the field experiments, total crop cover was decreased in all the droughted treatments (halved in some cases) for at least part of the season. Consequently, these treatments intercepted 12% less light, which in combination with a 16% decrease in the dry matter/light conversion coefficient, led to the decrease in growth. The decrease in conversion coefficient was due to temporary closure of the stomata rather than a function of drought-induced damage to the photosynthetic mechanism. The absolute effect of drought remained the same irrespective of whether the plants were infected with beet yellows virus, i.e. there was no interaction between the two stresses. The reasons for this lack of interaction are discussed but it is likely that the stress effects were mediated at different times of the day and season.
Ammonia (NH3) volatilization may decrease the fertilizer efficiency of surface-applied slurry and may cause the unwanted deposition of nitrogen (N) in oligotrophic ecosystems. We studied the effect of soil water content on the infiltration of slurry liquid and how infiltration affected NH3 volatilization. NH3 volatilization was measured with dynamic chambers through which air was drawn continuously. Slurry spiked with bromide (Br) to trace slurry infiltration was applied to a loamy sand in steel cylinders (diameter 6.7 cm and height 12 cm) adjusted to water contents of 0.01, 0.08, 0.12 and 0.19 g H2O per g soil (g g(-1)). At different time intervals after slurry application the soil columns were cut into slices and Br-, ammonium (NH4+) and nitrate (NO3-) concentrations were determined. At soil water contents > 0.12 g g(-1) nitrate content increased significantly from 24 to 72 h, and at 96 h NO3- content was equivalent to 75-130% of the NH4+ present at 0.5 h after slurry application. Nitrification may have contributed to a low NH3 volatilization from 24 to 96 h by reducing NH4+ concentration and contributing to acidity, and most of the NH3 volatilization occurred, therefore, during the first 24 h after application. Low soil water content enhanced the infiltration of slurry liquid and hence the mass transport of NH4+ into the soil. Transport of NH4+ by diffusion, on the other hand, was highest at the highest water content. Transport of NH4+ from the slurry at the soil surface down into the soil at 0.01 g g(-1) reduced NH3 volatilization to c. 70% of the volatilization from slurry applied to soils at higher water contents. Diffusion of NH4+ into the soil did not significantly decrease NH3 volatilization.
The potential use of faecal n-alkanes for estimation of intake and diet composition over periods of 1-2 days was assessed in two experiments. The aim was Co determine the accuracy with which intake and diet composition could be estimated by characterizing faeca.l excretion of n-alkanes following a discrete dose as opposed to steady state kinetics used in previous work. In the first experiment, 16 sheep were fed mixtures of spinach (rich in C-31-alkane) and cabbage (rich in C-29-alkane) in known proportions and amounts for two days. Artificial n-alkanes (C-28- and C-32- alkane) were dosed on four occasions during this time. Total intakes were controlled at 0.2, 0 3, 0 4 or 0 5 kg dry matter (DM) per day and nominal amounts of spinach offered (as a proportion of the total diet) were 0 00, 0.15, 0 30 and 0 45. Each sheep received a unique combination of intake and dietary proportions (four intake rates x four proportions). Sheep were fed fresh grass (timothy, Phleum pratense) before and after feeding spinach and cabbage. Sequential rectal grab samples of faeces were collected at regular intervals and total faecal collections were carried out over 144 h from the start of the spinach/cabbage feeding period to obtain samples for n-alkane analysis. In the second experiment, fresh grass was sprayed with two combinations of artificial n-alkanes (C-28- and C-32- or C-28- and C-36-alkane) and fed to 16 sheep over a 24 h period. Each sheep received one of four intake rates(0 8, 1 0, 1 2 or 1 4 kg DM/day) and, within intake rates, each sheep received one of four different proportions of the herbage sprayed with the combinations of n-alkanes (0 2, 0 4, 0 6 or 0 8), in a similar fashion to the first experiment. In order to estimate intake, C-26- and C-34- alkanes were dosed at the start of the feeding period. Faecal sampling procedures were the same as those in the first experiment. Different parameters of faecal excretion curves of dosed and natural n-alkanes were used to estimate dietary proportions and intake. Parameters tested included area under the excretion curve and curve maximum. Dietary proportions were calculated using an iterative minimization procedure employing faecal and herbage n-alkane concentrations. Intakes were estimated using ratios of dosed:natural faecal n-alkanes. The best estimates of dietary proportions were obtained using faecal concentrations at a single point in time in both experiments (> 80 % variation explained for regressions of estimated v. actual proportions). Intake estimates required the calculation of the: area under the excretion curve to obtain acceptable estimates (70-90% variance explained for regressions of estimated v. actual intakes in Expt 2). The experiments demonstrate that precise estimates of diet composition can be obtained using single faecal samples following consumption of simple herbage mixtures over 24-48 h. Intake may also be estimated using this technique provided that a series of faecal samples are collected over 4-5 days following the period of ingestion.
The effects of spring top-dressed applications of broiler litter, pig slurry and cattle slurry on winter wheat and winter barley yield and quality were investigated on a field scale at three UK sites between 1992 and 1994, using commercially available application equipment. Broiler litter was applied at rates ranging from 5.3 to 8.8 t/ha, and slurries from 54 to 89 m(3)/ha. Few practical problems were encountered when spreading broiler litter, but when spreading cattle slurry there was some crop damage and soil compaction from the tanker wheelings adjacent to tramlines. Coefficients of variation for manure spreading using commercial spreaders ranged from 20 to 32%. Spring applied manures increased yields of winter wheat and winter barley, and lowered optimum inorganic fertilizer nitrogen (N) rates. When the N efficiency of the manures was compared to that of inorganic fertilizer N, broiler litter N efficiencies ranged from 10 to 49%, cattle slurry was c. 30% and pig slurry c. 50%. The experiments demonstrated that poultry litters and slurries can be applied successfully to growing cereal crops in spring as part of an integrated policy for N supply.
Two experiments were conducted, at ADAS Drayton in the autumn and winter 1996/1997, to compare methane (CH4) emissions from sheep housed either in a polytunnel system or in open-circuit respiration chambers. In each system, the sheep received maintenance levels of either cut grass or high temperature dried grass pellets (HTDG). All experiments in the tunnel were conducted on concrete to avoid any interactions of the CH4 with the soil/plant environment. The results suggested that CH, production from the open-circuit chambers was greater than from the tunnel system (26.9+/-0.46 v. 31.7+/-0.351/kg dry matter intake (+/-S.E.) for open circuit respiration chambers and tunnel, respectively). Recovery tests gave similar results for both systems (95.5-97.9% for tunnels and 89.2-96.7% for chambers), and confirmed that both methods give good quantitative recovery of added CH4, and can therefore be assumed to provide reliable estimates of emissions from animals. There is no technical explanation, therefore, for the different estimates of emissions provided by the two systems. Further studies are required to understand the reasons for the differences and in particular, the possible links between animal behaviour induced by the two systems and CH4 emission rates.
A rotational grazing experiment using weaner deer was conducted at Palmerston North, New Zealand, during the autumn, winter and spring, to compare the voluntary feed intake (VFI), liveweight gain (LWG) and carcass production of deer grazing chicory with those grazing perennial ryegrass/white clover pasture. Deer were either treated with anthelmintic at 3-weekly intervals (T) or anthelmintic was withheld until trigger-treatment (TT) criteria were attained. Pure red and 0.75 red:0.25 elk hybrid stags and hinds were given forage allowances of 5 kg DM/deer/day in autumn and early-mid winter, 6 kg DM/deer/day in late winter and 7 kg DM/deer/day in spring. Deer grazed chicory or pasture in autumn and spring, with all deer combined on pasture during winter when chicory was dormant. Organic matter digestibility of diet selected was greater for chicory than for pasture in both autumn and spring. Anthelmintic-treated deer grazing pasture in autumn had significantly higher VFI and LWG, contributing to higher carcass weights, than TT deer. Anthelmintic treatment had no effect on these measures for deer grazing chicory in autumn. Clinical signs of lungworm infection were evident in pasture TT deer during autumn and winter, and in chicory TT deer grazing pasture during winter. Faecal egg counts (FEC) were significantly greater for pasture TT deer during autumn and early winter than all other groups. Faecal lungworm larval counts (FLC) were significantly greater for chicory TT deer following transfer to pasture, than for all other groups in early winter, although both FEC and FLC were low. Faecal larval counts were poorly related to clinical signs of lungworm infection during autumn, but were a better guide in winter. Plasma pepsinogen concentrations appeared unrelated to gastrointestinal parasite infection. Trigger-treated deer grazing pasture required five anthelmintic treatments during autumn and winter. The chicory TT group required no anthelmintic treatment when grazing chicory during autumn, but required two treatments after transfer from chicory to pasture during winter. There was no effect of anthelmintic regime on VFI and LWG in spring, and LWG was greater for deer grazing chicory than those grazing pasture. Hybrid deer had greater spring LWG and carcass weights than red deer when grazing chicory, but similar LWG and carcass weights when grazing pasture. It was concluded that grazing chicory offers the potential for reducing anthelmintic use in farmed weaner deer, particularly during autumn.
The pollination requirements of West Indian cherry (Malpighia emarginata DC) were investigated in NE Brazil through observations of flower morphology, floral rewards, anthesis, anther dehiscence, stigma receptivity, pollen cross and self-compatibility and proportion of fruit set. Potential insect pollinators and their foraging behaviour were also studied, and the pollination efficiency of the most frequent flower visitor, the bee Centris tarsata Smith (Anthophoridae), was assessed using single visits to flowers. It was shown that the West Indian cherry flower has a short lifespan, thus requiring pollination on the day of anthesis, when both cross- and self-pollen grains set fruit. The flower can potentially be pollinated by an array of insect visitors, but only oil-collecting bees of the genus Centris find it very attractive. Centris tarsata appeared as the main pollinator of West Indian cherry in the area studied, and farmers are advised to encourage its presence in orchards. Despite high levels of natural pollination, only 30% of flowers set fruits. It is suggested that a high proportion of abnormal ovule development may be responsible for low fruit set where pollination is satisfactory, and that West Indian cherry varieties showing a lower percentage of such abnormalities should be selected for.
Dry matter intake is one of the major factors limiting milk production in dairy cows, although the quantity of food consumed by an individual cow when housed and fed as part of a group is rarely known. Such information would permit more precise ration formulation, concentrate allocation and selection of cows according to efficiency of milk production. Alkanes have been used with sheep and cattle to estimate feed intake under grazing conditions and could provide a technique for measuring intake in housed dairy cows. The purpose of this study was to examine alkanes C-32 and C-36, in combination with alkane C-33, as indigestible markers for estimating intake of housed dairy cows fed on different diets under experimental and commercial conditions. Three experiments were conducted with hay-based diets (Expt 1), silage only diets (Expt 2) and a diet consisting of a silage-based basal ration plus concentrates (Expt 3). Animals were dosed once daily with C-32 and C-36, either on filter papers (Expts 1 and 2) or as part of a specially prepared concentrate (Expt 3). Faecal recoveries of alkanes ranged from 0.88 to 0.99. Over the range of intakes found in the three experiments (6-24 kg DM/d), the r(2) values for estimated versus actual dry matter intakes ranged from 0.81 to 0.99. It is concluded that alkanes could provide a useful technique for estimating intake in dairy cows housed and fed in groups.